3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) (i.e., the improvement of a Universal Mobile Telecommunications System (UMTS)) is introduced as 3GPP release 8. 3GPP LTE uses Orthogonal Frequency Division Multiple Access (OFDMA) in downlink and uses Single Carrier-Frequency Division Multiple Access (SC-FDMA) in uplink. Multiple Input Multiple Output (MIMO) having a maximum of 4 antennas is adopted. Recently, a discussion on 3GPP LTE-Advanced (LTE-A) which is the evolution of 3GPP LTE is in progress.
Technology introduced in 3GPP LTE-A includes a carrier aggregation, a relay, etc. A 3GPP LTE system is a single carrier system that supports only one bandwidth (i.e., one component carrier) of {1.4, 3, 5, 10, 15, 20} MHz. However, LTE-A is introducing multiple carriers employing a carrier aggregation. A component carrier is defined by a center frequency and a bandwidth. A multiple carrier system uses a plurality of component carriers having a smaller bandwidth than the entire bandwidth.
A user equipment consistently performs measurement in order to maintain the quality of a radio link with a serving cell from which service is being provided. A cell or frequency that is the subject of measurement is called a measurement object, and a report configuration independently causing a report on a measurement result is associated with each measurement object. The user equipment performs measurement for measurement objects and, if report configurations are satisfied, reports measurement results to a base station.
In a multiple carrier system, if measurement results for a plurality of all component carriers are reported, a load for reports on the measurement results may be increased according to an increase in the number of component carriers. Furthermore, user equipment does not use all the component carriers according to the capability of the user equipment or a cell environment.
In a wireless communication system, there is a need for a scheme capable of more efficiently reporting measurement results for a plurality of component carriers.